1. Field of the Invention
The present invention relates to a system and a method for authenticating a person using biometrics information such as fingerprint, palm print, finger shape, palm shape, voice, retina, iris, face image, dynamic signature, blood vessel pattern, keystroke, or the like, and a registering apparatus, an authenticating apparatus, and a pattern information input medium for the system.
2. Description of the Related Art
In recent years, there is growing interest in security with wide introduction of computers into social systems. ID cards or passwords are heretofore used as a means for verifying a person when he or she enters into a computer room or uses a terminal. However, this leaves a lot of problems in respect to security.
As a more reliable means than passwords for verifying a person, a personal authenticating technique using biometrics information such as fingerprint, palm print, finger shape, palm shape, voice, retina, iris, face image, dynamic signature, blood vessel pattern, keystroke, or the like, attracts public attention. Verification of a person using biometrics information inherent in a person produces a very high reliability.
In a personal authentication system using such biometrics information, biometrics information on each person who should be authenticated in the system is obtained, characteristic data is extracted from the biometrics information, and the characteristics data is beforehand registered as registry characteristic data of each person to be authenticated. When the biometrics information is verified in order to authenticate a person, biometrics information on the person to be authenticated is obtained, characteristics data to be authenticated is extracted from the biometrics information, the above characteristic data to be authenticated is compared and matched with the registry characteristic data registered beforehand, and a rate of matching of these two sorts of characteristic data is calculated. When the rate of matching between the registry characteristic data and the characteristic data to be authenticated is not less than a predetermined value (or exceeds a predetermined value), the person to be authenticated is determined to be the registered person.
Next, personal authentication using fingerprint, which is one piece of biometrics information that can be used to verify a person, will be briefly described. Fingerprint is said to have two characteristics that are “no two persons have exactly the same fingerprint” and “the fingerprint of anyone individual remain unchanged through life”. Therefore, fingerprint is considered to be a strong means for verifying a person. A lot of researches and developments relating to personal authentication systems using fingerprints are made in recent years.
Fingerprints are minute irregularities on fingertips of a person. Ranges of the minute irregularities are called ridges. The ridges form various patterns inherent to a person. When the ridge is followed, a bifurcation at which the ridge branches (bifurcation) or a dead-end (ending) appears. Distribution of bifurcations and endings differs in individuals, which is thus called minutiae of fingerprints. Matching of a state of distribution of the minutiae is used as a strong means to specify a person.
When personal authentication is performed using such a fingerprint as biometrics information, coordinates of an intersection of ridges of the fingerprint, coordinates of a center of the fingerprint, coordinates of a delta of the fingerprint, a direction of a ridge of the fingerprint, a distance between minutiae, the number of ridges between minutiae of the fingerprint, etc. are extracted along with a position (coordinates), a type, and a direction of the minutia described above.
In a personal authentication system using fingerprints, fingerprint characteristic data of a person is beforehand registered. Namely, a user (person) of the system inputs fingerprint image data into a predetermined apparatus, characteristic data is extracted from the fingerprint image data and registered as registry characteristic data.
When fingerprint image data of an authenticating object person is obtained by a fingerprint scanner at the time of verification, characteristic data to be authenticated is extracted from the fingerprint image data, and it is verified whether the characteristic data to be authenticated matches the registry characteristic data registered beforehand. When a rate of matching is not less than a predetermined value, it is determined that the person to be authenticated is the person registered in the personal authentication system.
Generally, a fingerprint pattern is obtained in a form of a fingerprint image, by photographing the image by a CCD camera while a finger is contacted with a special optical system, or by detecting only a ridged part on the skin by a capacitance sensor. However, when an image of an unclear fingerprint, that is, an blurred image of a fingerprint or an image of a fingerprint in which ridges are adhered by sweat, is obtained, it is impossible to verify whether a person to be authenticated is a registered person because a rate of matching becomes less than the predetermined value when the verification is performed.
In another case, it is likely that a rate of matching becomes less than the predetermined value due to unexpected factors in the personal authorization system using biometrics information. As the factors, there are dryness, roughness, etc. of the fingertips in winter time along with deformation due to injury in the case of personal authentication using a fingerprint, and deformation due to injury or disease in the case of person authorization using a face or an iris.
In the above-mentioned personal authorization technique using biometrics information, when a rate of matching becomes less than the predetermined value and the personal authentication thus results in failure due to any factor, the process is completed in consideration that the person is not the person himself/herself (registered person), or personal authentication is performed by inputting a password or the like as a measure for relief. When the latter means is used, a device for inputting a password such as a ten key pad, a keyboard or the like is beforehand provided to the apparatus for fingerprint verification, and the person to be authenticated inputs a password registered beforehand from the device.
When the authentication is failed because of an input error of the biometrics information or the like, re-verification is performed again by re-inputting the same biometrics information, which sometimes allows normal authentication. However, when it becomes impossible to exceed a predetermined rate of matching due to a factor such as injury or the like, a system without a measure for relief cannot authenticate the person to be authenticated as the person himself/herself (registered person).
When a measure for relief by inputting a password is employed, an advantage of personal authentication using biometrics information that can eliminate a trouble of keyboard inputting is lost, which leads to complexity or an increase in cost of the system.
When personal authentication is failed, as another idea, biometrics information which is different from the one that has been used when the authentication was failed, is obtained to authenticate the person (for, example, the authentication is performed using a face or an iris when the personal authentication using a fingerprint is failed). In order to realize this system, it is necessary to provide plural kinds of biometrics information inputting apparatus to each of the registering apparatus and the authenticating apparatus. Namely, a biometrics information inputting apparatus (for example, an apparatus that obtains a face or an iris as image data) of a different type from the biometrics information inputting apparatus used in the first verification (primary verification) is required, which also leads to complication or an increase in cost of the system.
In the personal authentication system using biometrics information, the user has to beforehand register registry characteristic data, as stated above. When a fingerprint is used as the biometrics information, the user inputs fingerprint image data in registration. However, it is not possible to register a person whose fingerprint is in unstable conditions due to dryness or roughness of the finger in winter time, or a person whose fingerprint cannot be primarily obtained due to injury or the like, which sometimes unables personal authentication. Therefore, a measure for relief in such case is further necessary.
When the measure for relief by inputting a password is employed to cope with it, it is necessary to provide a device such as a ten key pad, a keyboard or the like, as stated above, which leads to complexity or an increase in cost of the system. Alternatively, it is considered that registry characteristic data is extracted from biometrics information which is different from the biometrics information that failed to be registered, and is registered (for example, a face or an iris is used to be registered when registry using, for example, a fingerprint is impossible). In order to realize this system, it is necessary to provide plural kinds of biometrics information inputting apparatuses, which also leads to complexity or an increase in cost of the system.